Method and apparatus for the introduction of carburetion materials into melted ferrous metal baths



June 14, 1966 A. CARL! ETAL 3,255,898

METHOD AND APPARATUS FOR THE INTRODUCTION OF CARBURETION MATERIALS INTO MELTED FERROUS METAL BATHS Filed March 2, 1964 2 Sheets-Sheet l INVENTORS Yfamo aw l/ bgwli ex K0 laJfo 105K" Mm MVW Q June 1966 A. CARLI ETAL 3,255,393

METHOD AND APPARATUS FOR THE INTRODUCTION OF CARBURETION MATERIALS INTO MELTED FERROUS METAL BATHS Filed March 2, 1964 2 Sheets-Sheet 2 Ray/ 144;:

-matic view of an apparatus according to the United States Patent Office 3,255,898 Patented June 14, 1966 6 Claims. Cl. 214-21 This invention relates to a process and devices for the introduction of treating materials into melted metal baths.

Particularly, but not exclusively, in the metallurgical industry, it is necessary to introduce some carbonaceous substances or the like into melted metal baths, to carry out chemical reactions and, particularly, to assure that a reduction of oxides be performed as soon as the said oxides are melted.

Generally, the addition of carbonaceous substances is made in order to give the desired carburizing to the metal, depending upon the requirements dictated by usage or further metallurgical treatment.

The known feeding devices have some drawbacks, the first of which is that it is not possible to have a uniform and continuous treatment of the melted metal bath, as the treating material is introduced into the melted bath through the surface of the liquid metal in the bath; The introduction of the treating material into the melted metal encounters difficulties, especially when such material is introduced into crucibles of substantial capacity; in order to avoid the deterioration of the feeders or the contact of their portions with the melted metal, they are placed in a raised position so that the treating material is introduced into the bath from above downwardly.

In this respect, therefore, even though possible damages caused to the feeder by the melted metals are avoided, other drawbacks are encountered, since the treatment of the melted-nietal is neither completed, uniform nor homogeneous, as required by the metallurgical art, in that the added material tends to remain at the top of the metal bath.

Moreover, the known feeders do not permit a continuous regulation of the introduction of the treating material into the melted metal bath, Whereas such regulation is essential due to technical and economical requirements.

This invention solves the above problem in a simple and practical manner, especially with respect to the uniformity of treatment of the melted metal bath, even when such bath is of a substantial volume and, therefore, there are substantial head pressures of the charge stock itself, without the danger of damaging some metallic portions of the device.

The process, according to the present invention, comprises introducing the treating material into the melted metal bath substantially below the surface of the liquid material in the bath.

The device for carrying out the process set forth above comprises at least an extrusion nozzle, the aperture of which is placed below the surface of the liquid material in the bath and which is connected with forcing means provided for the forcing of the material into the bath. For example, the forcing means comprise at least a screw conveyor to assure the continuity of the feeding.

The invention will be further explained with reference to the drawings in which:

FIG. 1 is a vertical axial section, partially diagrampreferred embodiment of the invention; and

FIG. 2 is a longitudinal, axial, partially sectional, partially diagrammatic view of an alternate embodiment of the invention.

The device comprises a shaft 10 connected by means of a suitable speed reducer with a driving motor, not illustrated.

With shaft 10 is integral a pinion 12 in mesh with a conical wheel 14 keyed on a spindle 16 carried in a conventional way by a casing 18 which supports also shaft '10. Spindle 16 is arranged, by way of example, either upright or horizontal or slightly inclined, and is integral with a screw conveyor 20 fitted in a sleeve 22 which terminates, at the lower end thereof, with a flange 24 secured on casing 18. A sleeve 22 at the lower end thereof has a lateral funnel 26 which leads into the chamber formed by sleeve 22.

The cross-section of duct 26 increases from the inlet to the outlet, that is toward the last mentioned chamber and the inlet of this duct is connected with a hopper, not illustrated, for feeding the treating material in the form of powder with a grain-size ranging within 0 and 20.

Sleeve 22 is connected with a complementary sleeve 28 which ends at the upper portion thereof with a flange 30 opportunely secured to the frame K of the crucible or some other member.

Flange 30 retains a bored plate 32 ofa suitable refractory material which forms an extrusion nozzle of which the bore or aperture 34 leads preferably into the bottom of the crucible or of the melting chamber of the furnace.

Sleeves 22 and 28 according to FIGURE 1 are rigidly connected with each other by means of bolts. A plurality of grooves, in conjunction with sleeves 38 and 40 and with connection fittings 42 and 44, form coils for the circulation of a cooling liquid. Instead, according to FIG- URE 2, where the main axis x-x is horizontal or slightly inclined, the connection between sleeve 28a and plate 30a is formed by a bent connection fitting 62.

The material flow section of said connection fitting gradually increases toward the inlet of the crucible accord ing to a law experimentally found which a function of the radius of the 'bend or curve and of its length, as well as the physical conditions of the material. The tapering of the fitting must range between 1:10 and 1:30. This is in order to assure that the granular material which passes through the fitting has the required conditions of compression and agglomeration while avoiding, on the other hand, occlusions, seizure or the like.

A simple, practical system for regulating the supplying rate, below the surface of liquid metal of the corrective material, comprises a suitable metering device which permits the quantity which is introduced into the forcing means to be varied at will.

The powdered material from the hopper passes through duct 26, enters the screw conveyor, in order to be compressed gradually so as to result, at the outlet of the aper-' ture 34, in a block of powdered material. This block is introduced into the bath of melted metal.

Such system of introduction permits that the mass of liquid metal be put into intimate contact with the treating material so that said treatment can be extended to the whole melted metal bath with regularity and uniformity.

The gases eventually developed during the'introduction of the material pass, in an upward direction, through the melted metal mass, thereby mixing said mass and extending the reaction throughout the entire bath. On the other hand, it is possible to perform easily and quickly the metering of the added materials, whether they be corrective, purifying or reacting agents of the melted mass. The block of material from the aperture 34 has such characteristics as to avoid that the melted metal enters and comes into contact with the metallic portions of the device, even when there are substantial metal head pressures. Modifications and changes can be made to the device as described and illustrated.

Sleeve 22 could have two or more ducts 26 for supplying the screw conveyor simultaneously or alternately with two or more powdered materials. The screw conveyor 20 could be made in such a manner as to allow that its pitch and/ or the height of the threads vary from the inlet to the outlet depending upon the usage requirements and characteristics of the powdered material involved.

Referring again to FIG. 2, the hopper 26a is combined with a chute 50, provided with a vibrator P. In order to avoid the clogging of the threads of the screw conveyor 20 and 2011 by the compressed material, bores 56 are drilled in said threads to allow pins 54 secured to sleeves 22a and 28a to pass through them.

Sleeve 28a ends with outlet 60 which is shaped so as to house a conical end 58 of the conveyor screw 20a; said conveyor screw is connected, by means of a fitting 62, with an extrusion nozzle 64, provided with cooling chamber 66 having fittings 68 and '70 therein.

Motor M for conveyor screw 20a is furnished with wheels 55, sliding on rails H.

It should be pointed out that the present invention also covers the furnace or the crucible which, for carrying out the process according to this invention, has one or more of the devices being considered applied to the bottom and/or the walls.

We claim:

1. A process for introducing at least one carburetion material into a crucible containing a melted metal bath comprising moving said carburetion material from storage, mixing and compressing said material to a desired compactness, and introducing the compacted material as a solid unit to the melted metal bath at a point below the surface of the liquid in the metal bath preferably at the lowermost portion of the crucible bottom.

2. A device for introducing carburetion materials into melted metal baths within a crucible comprising means to store the carburetion material, means for pressing the carburetion material from a granular state to a compacted state, means to move the carburetion material from said storage means to said pressing means, at least one extrusion nozzle, said nozzle passing through a wall of said crucible and being directed towards a point in the crucible below the liquid level of the molten metal, means connecting said pressing means to said extrusion nozzle, means for forcing the carburetion material through said nozzle into the metal bath, said means for moving the carburetion material from storage controlling the amount of material to be supplied to the forcing means during a time unit Without varying the speed of the forcing means thereby insuring uniform deposition of the compacted treated material in the melted metal bath.

3. A device according to claim 2 wherein said forcing means comprises a screw conveyor.

4. A device according to claim 3 wherein the screw conveyor tapers inwardly towards the end adjacent said crucible.

5. A device according to claim 3 wherein the longitudinal axis of the forcing means is at an angle other than perpendicular to the surface of the crucible.

6. A device according to claim 5 wherein the means connecting said forcing means with said eXtruder nozzle is a curved conduit, said curved conduit having a given taper which falls within the range of from 1:30 to 1:10, the cross sectional area of said conduit increasing from the outlet of the forcing means to said nozzle.

References Cited by the Examiner UNITED STATES PATENT S 1,834,631 12/1931Mulholland.

2,142,984 1/1939 Thurman.

2,452,453 10/1948 Graham 2l4-21 2,556,391 6 /1951 Hawk 198-213 GERALD M. FORLENZA, Primary Examiner.

HUGO O. SCHULZ, R. SHERIDAN, Examiners. 

1. A PROCESS FOR INTRODUCING AT LEAST ONE CARBURETION MATERIAL INTO A CRUCIBLE CONTAINING A MELTED METAL BATH COMPRISING MOVING SAID CARBURETION MATERIAL FROM STORAGE, MIXING AND COMPRESSING SAID MATERIAL TO A DESIRED COMPACTNESS, AND INTRODUCING THE COMPACTED MATERIAL AS A SOLID UNIT TO THE MELTED METAL BATH AT A POINT BELOW THE SURFACE OF THE LIQUID IN THE METAL BATH PREFEREBLY AT THE LOWERMOST PORTION OF THE CRUCIBLE BOTTOM.
 2. A DEVICE FOR INTRODUCING CARBURETION MATERIALS INTO MELTED METAL BATHS WITHIN A CRUCIBLE COMPRISING MEANS TO STORE THE CARBURETION MATERIAL, MEANS FOR PRESSING THE CARBURETION MATERIAL FROM A GRANULAR STATE TO A COMPACTED STATE, MEANS TO MOVE THE CARBURETION MATERIAL FROM SAID STORAGE MEANS TO SAID PRESSING MEANS, AT LEAST ONE EXTRUSION NOZZLE, SAID NOZZLE PASSING THROUGH A WALL OF SAID CRUCIBLE AND BEING DIRECTED TOWARDS A POINT IN THE CRUCIBLE BELOW THE LIQUID LEVEL OF THE MOLTEN METAL, MEANS CONNECTING SAID PRESSING MEANS TO SAID EXTRUSION 